Is there a way to modify the page title with React-Router v4+?

<Route /> components have render property. So you can modify the page title when location changes by declaring your routes like that:

<Route
  exact
  path="/"
  render={props => (
    <Page {...props} component={Index} title="Index Page" />
  )}
/>

<Route
  path="/about"
  render={props => (
    <Page {...props} component={About} title="About Page" />
  )}
/>

In Page component you can set the route title:

import React from "react"

/* 
 * Component which serves the purpose of a "root route component". 
 */
class Page extends React.Component {
  /**
   * Here, we define a react lifecycle method that gets executed each time 
   * our component is mounted to the DOM, which is exactly what we want in this case
   */
  componentDidMount() {
    document.title = this.props.title
  }
  
  /**
   * Here, we use a component prop to render 
   * a component, as specified in route configuration
   */
  render() {
    const PageComponent = this.props.component

    return (
      <PageComponent />
    )
  }
}

export default Page

Update 1 Aug 2019. This only works with react-router >= 4.x. Thanks to @supremebeing7

Updated answer using React Hooks:

You can specify the title of any route using the component below, which is built by using useEffect.

import { useEffect } from "react";

const Page = (props) => {
  useEffect(() => {
    document.title = props.title || "";
  }, [props.title]);
  return props.children;
};

export default Page;

And then use Page in the render prop of a route:

<Route
  path="/about"
  render={(props) => (
    <Page title="Index">
      <Index {...props} />
    </Page>
  )}
/>

<Route
  path="/profile"
  render={(props) => (
    <Page title="Profile">
      <Profile {...props} />
    </Page>
  )}
/>

In your componentDidMount() method do this for every page

componentDidMount() {
  document.title = 'Your page title here';
}

This will change your page title, do the above mentioned for every route.

Also if it is more then just the title part, check react-helmet It is a very neat library for this, and handles some nice edge cases as well.

Picking up from the excellent answer of phen0menon, why not extend Route instead of React.Component?

import React, { useEffect } from 'react';
import { Route } from 'react-router-dom';
import PropTypes from 'prop-types';

export const Page = ({ title, ...rest }) => {
  useEffect(() => {
    document.title = title;
  }, [title]);
  return <Route {...rest} />;
};

This will remove overhead code as seen below:

// old:
  <Route
    exact
    path="/"
    render={props => (
      <Page {...props} component={Index} title="Index Page" />
    )}
  />

// improvement:
  <Page
    exact
    path="/"
    component={Index}
    title="Index Page"
  />

Update: another way to do it is with a custom hook:

import { useEffect } from 'react';

/** Hook for changing title */
export const useTitle = title => {
  useEffect(() => {
    const oldTitle = document.title;
    title && (document.title = title);
    // following line is optional, but will reset title when component unmounts
    return () => document.title = oldTitle;
  }, [title]);
};